Users often abandon such trolleys after use at a considerable distance from the point at which they were taken. It is then necessary to find the trolleys and to return them to a starting point where they are again left at the disposition of travellers or customers. This can be relatively expensive. It can also happen that trolleys are not found, or that they are found damaged.
Systems have already been proposed to encourage users to return such trolleys after use. These systems are generally located at the entrance to a trolley storage or collecting area, and comprise means for detecting the presence of a trolley at the entrance to the collecting area, and means for dispensing some kind of reward when a trolley is effectively returned.
Naturally, it is necessary to prevent such a system from dispensing a reward in the event of a fraud or an attempted fraud, for example of the kind in which a person moves a trolley back and forth past a trolley detector to simulate the return of a large number of trolleys in order to obtain a corresponding number of rewards. However, presently known systems that are immune to such frauds are relative complex and expensive.
Preferred embodiments of the present invention provide a system of the type described above for encouraging users to return vehicles such as trolleys, but in which the system is less complex than prior systems and is therefore capable of being made more cheaply, while nevertheless providing a high degree of security against attempted frauds.